1. Field of the Invention
The present invention relates to a control apparatus for a hydraulic excavator, and more specifically, to a control apparatus for a hydraulic excavator for controlling a hydraulic excavator using a fuzzy inference.
2. Description of the Related Art
The work machine such as a hydraulic excavator performs many works such as a scattering work, a slope tamping work, a normal finishing work, a crane work, a press-excavating work, a loading work, a swing ground-leveling work, a simple excavating work, a channel excavating work, a horizontal ground-leveling work, etc., and the operating characteristics suitable for these works are different. Therefore, some work modes are prepared, and the work mode has been switched by performing switching operation manually by an operator. However, since the switching operation is complicated, the work mode has not been digested for use sufficiently.
In view of the foregoing, a technique for automatically carrying out a work discrimination in order to switch the work mode has been developed. However, in the actual excavating work, only a specific work is less accomplished, and a plurality of works are combined, for example, such that the excavating work is first carried out, and the finishing work is then carried out. Switching to these works is often carried out.
It is now supposed that the maximum flow-rate of a hydraulic pump is set to 100% for the simple excavating work, and 70% for the normal finishing work, respectively. It is further supposed that an operator performed the work for shifting to the simple excavation from the normal finishing. Then, the maximum flow-rate of the hydraulic pump rapidly changes from 70% to 100% whereby the operator feels a considerable shock, as a consequence of which the operability of the hydraulic excavator is sometimes greatly impaired.
Further, historical data of each operating amount for a fixed time (for example, for 15 seconds) are necessary in order to extract each characteristic amount necessary for work discrimination. When an operator switches the operation within the fixed time, data for different kind of work are mixed within the historical data of the operating amount, and an error tends to occur in discrimination of work. Accordingly, where an operator switches the operation from the excavating work to the operation for the normal finishing work, operation different from the normal finishing work is discriminated immediately before the result of discrimination is decided to the excavating work, as a consequence of which the work is sometime switched to a work mode that is not intended by an operator. A sense of incongruity of operation caused by switching to the work not intended as described above is conspicuously felt by an operator and as a result, the operability of the hydraulic excavator is sometimes impaired.
It is an object of the present invention to provide a control apparatus for a hydraulic excavator capable of minimizing a shock or a sense of incongruity when operation is switched to enhance an operability of a hydraulic excavator.
A control apparatus for a hydraulic excavator according to the present invention comprises an operating amount detection means for detecting operating amounts of operating levers corresponding to actuators for works of a hydraulic excavator; a characteristic amount operation means for operating a characteristic amount showing a characteristic of operation of a hydraulic excavator on the basis of the operating amount detected; a membership function memory means for storing a plurality of membership functions for a fuzzing inference preset corresponding to the characteristic amounts by kinds of work; a fitness operation means for operating fitnesses relative to the works of the characteristic amount operated by applying the operated characteristic amount to the stored membership function; an operating characteristic set value memory means for storing operating characteristic set values preset corresponding to operating characteristics by kinds of work; and an operating characteristic output means for outputting fitnesses operated corresponding to a plurality of kinds of work and operating characteristics for controlling a hydraulic excavator on the basis of the operating characteristics set values stored.
In this case, operating amounts of operating levers corresponding to actuators for works of a hydraulic excavator are detected by an operating amount detection means, a characteristic amount showing a characteristic of operation of a hydraulic excavator on the basis of the operating amount detected is operated by a characteristic amount operation means, a plurality of membership functions for a fuzzing inference preset corresponding to the characteristic amounts by kinds of work are stored by a membership function memory means, and the characteristic amounts operated are applied to the membership functions stored whereby fitnesses relative to the works of the characteristic amounted operated are operated by a fitness operation means. At this time, operating characteristic set values preset corresponding to operating characteristics by kinds of work is stored in an operating characteristic set value memory means, and an operating characteristic output means fitnesses operated corresponding to a plurality of kinds of work and operating characteristics for controlling a hydraulic excavator on the basis of the operating characteristics set values stored are output by an operating characteristic output means. That is, the operating characteristic set value corresponding to a single kind of work is not output without modification but an output value of the operating characteristic obtained from the fitnesses corresponding to a plurality of kinds of work and the operating characteristic set values are output. Thereby, a plurality of fitnesses are generally reflected on the output values of the operating characteristics.
More specifically, for example, a relationship between the characteristic amount and the work is described by a fuzzing rule in advance, so that the fitness to each rule is calculated on the basis of a preset member function, and the output value of the operating characteristic is obtained by an average of load with the fitness to each rule regarded as a weight.
Thereby, the operating characteristic is not switched to a predetermined value in an ON-OFF manner, but an intermediate value is output. For example, where the maximum flow-rate of a hydraulic pump is similar to that of the aforementioned relative art, its output value is 85% which is an intermediate between 100% and 70%.
Accordingly, for example, even where an operator performs the work from the normal finishing to the simple excavation, an intermediate output value other than the operating characteristic set value stored in advance before and after switching of work can be made as a control valve, and therefore, the maximum flow-rate of the hydraulic pump is not changed stepwise, but changed staircase-wise to make the switching of the operating characteristic smooth.
Further, even where data of different kinds of works are mixed in the operating amount historical data, the control in consideration of fitnesses is employed, as compared to the ON-OFF switching, and even an erroneous discrimination, i.e., where the fitness of work that is not intended by an operator increase, the influence on the operating characteristics is averaged to reduce a sense of incongruity of operation.
Further, suppose that the operating characteristic set values are grouped by kinds of work having the same operating characteristic, and the operating characteristic for controlling a hydraulic excavator is output on the basis of the fitness and the operating characteristic set value by work group, a specific operating characteristic appears repeatedly to enable preventing the operating characteristic form being stressed.
More specifically, for example, a relationship between each characteristic amount and each work group is described in a fuzzy rule, the fitness to each rule is calculated on the basis of a preset membership function, and an output value of the operating characteristic is obtained by an average of load with the fitness to the rule being a weight using the operating characteristic values set by each work group.
As a result, in any case, it is possible to minimize a shock or a sense of incongruity when operation is switched to enhance the operating characteristic of the hydraulic excavator.